Carbohydrate Polymers最新文献

Natural polysaccharides have complex structural properties and a wide range of health-promoting effects. Accumulating evidence suggests that the effects are significantly mediated through fermentation by gut microbiota. In recent years, the relationship between the structures of natural polysaccharides and their properties in regulating gut microbiota has garnered significant research attention as researchers attempt to precisely understand the role of gut microbiota in the bioactivities of natural polysaccharides. Progress in this niche, however, remains limited. In this review, we first provide an overview of current research investigating this structure-property relationship. We then present a detailed correlation analysis between the structural characteristics of 159 purified natural polysaccharides and their effects on gut microbiota reported over the past two decades. The analysis revealed that diverse gut bacteria show specific correlations with the molecular weight, glycosidic linkages, and monosaccharide composition of natural polysaccharides. Multifaceted molecular mechanisms, including carbohydrate binding, enzymatic degradation, and cross-feeding, were proposed to be collectively involved in these correlations. Finally, we offer our perspective on future studies to further improve our understanding of the relationship between polysaccharide structure and gut microbiota regulation.

The management of wounds infected with drug-resistant bacteria represents a significant challenge to public health globally. Nanotechnology-functionalized photothermal hydrogel with good thermal stability, biocompatibility and tissue adhesion exhibits great potential in treating these infected wounds. Herein, a novel photothermal hydrogel (mCS-Cu-Ser₁) was prepared through in situ mineralization in the hydrogel networks and ion cross-linking driven by copper ions (∼3 mM). Self-assembling polyphosphate sericin nanoparticles (Ser NPs) formed by an ultrasound-assisted anti-solvent method were as mineralization templates and gallic acid-grafted chitosan (mCS) was prepared as the sole matrix. Grafting of polyphenols and cross-linking of copper ions endowed mCS-Cu-Ser₁ with injectable, skin-adhesive and self-healing characteristics. Due to the nonradiative relaxation of Cu²⁺ electron-hole pairs of copper phosphate on the surface of Ser NPs and the molecular thermo-vibrational effect of the mCS-Cu complex, mCS-Cu-Ser₁ rapidly warmed up to 50 °C within one minute under near-infrared (NIR) irradiation. Integrating such excellent photothermal properties with antimicrobial activity and intracellular reactive oxygen species scavenging from mCS, mCS-Cu-Ser₁ + NIR effectively accelerated methicillin-resistant Staphylococcus aureus (MRSA) infected wound healing. This work develops a novel dressing for the treatment of MRSA-infected wounds and provides some reference for the preparation of multifunctional acid-free chitosan hydrogels.

Levan, a β(2 → 6) linked D-fructofuranosyl polymer, is gaining significant attention in basic and applied research. It has been demonstrated that most properties are related to levan molecular weight but also its β(2 → 1) branching degree. In this paper the relationship between levan branching degree, particle size, and molecular weight is reviewed, exploring also how these structural parameters influence levan susceptibility to exo- and endolevanase hydrolysis for levans produced by three recombinants bacterial levansucrases. We found almost no association between molecular weight and neither particle size nor branching degree in levans described in the literature including those evaluated in this work. We also found that all evaluated levans form spherical nanoparticles. Interestingly, in enzyme assays with the synthesized levans, increasing branching and decreasing particle size are inversely associated with lower exolevanase (Bs-SacB) and endolevanase (Bl-LevB) hydrolysis rates. After a limited but exclusive β(2 → 6) exolevanase hydrolysis a limit-levan structure may be obtained. In the case of endolevanase hydrolysis, branching not only decreases endolevanase activity but also affects the type of oligosaccharides obtained, probably due to limited access to the enzyme to linear regions of the polymer.

Yeast immobilization systems can recoup yeast losses in continuous batch fermentation and relieve substrate or product inhibition. We report the use of solution blow spinning process to efficiently prepare polyhydroxyalkanoate (PHB) /konjac glucomannan (KGM) nanofiber membranes as immobilization carriers for Saccharomyces cerevisiae. The prepared PHB/KGM nanofiber membranes had fiber diameters similar to the scale of yeast cells. Incorporating KGM significantly enhanced the porosity (from 87.21 % to 91.74 %), crystallinity, and hydrophilicity (reducing water contact angle from 135.8° to 110.1°), while increasing the specific surface area (from 10.24 to 17.79 m²/g) of pure PHB nanofiber membranes. Thermal stability was maintained (degradation temperatures above 250 °C). These changes enhanced the force between the nanofiber membranes and the cells and facilitated their autoimmobilization on the nanofiber membranes. The highest yeast immobilization efficiency of 87.93 % could be achieved at a KGM addition ratio of 400:2. Yeast showed no loss of cellular activity on the immobilized carriers of natural materials and maintained or even improved fermentation kinetics during at least three consecutive alcoholic fermentations These findings indicate that PHB/KGM nanofiber membranes can serve as effective carriers for yeast immobilization, promoting the sustainable production of fermented foods.

The traditional foams can only block heat loss, and cannot effectively store and release heat energy on demand to extend the insulation time. In this work, the paraffin-rich monolayer microcapsules were prepared using negatively charged phosphorylated cellulose nanofibers (CNF) as the emulsifier of Pickering emulsion. The positive chitosan was assembled on the surface of the monolayer microcapsules through an electrostatic layer-by-layer self-assembly method to prepare the bilayer microcapsules. Konjac glucomannan (KGM) was used as the dispersive medium of bilayer microcapsules and the gel skeleton to prepare phase change foam through freeze-drying. The foams exhibited excellent water resistance, mechanical properties, and thermal stability. The double-shell structure of chitosan/CNF microcapsules and the capillary action of KGM foam could effectively inhibit paraffin leakage. Moreover, the paraffin content of KCCP-4 foam was as high as 72.7 %, and the enthalpy of melting and crystallization were as high as 149 J/g and 146 J/g, respectively. The thermal conductivity and infrared thermal imaging results demonstrated that the KCCP-4 foam had excellent thermal insulation and energy storage properties. This study provides a simple and effective design strategy for the application of thermal insulation and energy storage foams in smart textiles.

Dietary fibers (DF) from plant-based foods promote health benefits through their physicochemical properties and fermentation by the gut microbiota, often studied in relation to changes in gut microbiota profile and production of gut microbiota-derived metabolites. Here, we characterized structural motifs (i.e., oligomers) produced during DF breakdown upon colonic fermentation and explored their interaction with toll-like receptors (TLRs) present on the surface of human intestinal and immune system cells. Wheat arabinoxylan (WAX) was subjected to in vitro colonic fermentation, with its structural motifs identified and tracked throughout the fermentation process. Using carbohydrate-active enzymes, six well-defined fractions of arabinoxylans and linear xylans identified during colonic fermentation were produced and tested for interaction with tool-like receptors (TLR)2 and TLR4 via reporter cell assay. The results showed structure-dependent effects, with TLR2 inhibition and TLR4 activation varying based on the degree of polymerization and branching. Molecular docking confirmed that minor structural changes in oligomers structure significantly influenced these interactions. The study supports the hypothesis that oligomers and polysaccharides affect cell receptors through complex, multi-receptor interactions, and highlights the potential for enzymatic tailoring of DF to create functional ingredients with targeted effects on human health.

Pickering emulsion template has aroused attention in the fabrication of porous composite materials. In this work, six nanoparticles including cellulose nanofiber/nanocrystal (CNF/CNC), chitin nanofiber/nanocrystals (ChNF/ChNC) and waxy/normal corn nanocrystal (WSNC/CSNC) were comparatively studied for their performance in fabricating porous composites with PDMS via Pickering emulsion templates. Among all, CNF and ChNF exhibited best emulsion stabilizing ability, while ChNF and ChNC at optimized concentrations enabled the formation of high internal phase emulsions with long-term stability of over 300 days. WSNC and CSNC with poorest emulsion stabilizing ability failed to obtain porous composites while the other four particles all formed porous composites with PDMS. The ChNF and ChNC composites displayed highest hydrophobicity, followed by the CNC composite. As adsorbents for diesel oil, the ChNF composite showed the highest adsorption capacity and adsorption selectivity, which could be easily recycled by simple mechanical squeezing. At optimized PDMS fractions, the ChNF composite could achieve continuous oil-water separation under vacuum with a highest separation efficiency of 98.9 % at high flux of 8862 L/h·m². This study revealed the association between nanoparticles and their composite materials fabricated from Pickering emulsion template, hopefully broadening the application of natural polymers in water treatment and related fields.

There is an emerging quest for fabrication of water-soluble fluorescent silver nanoclusters (AgNCs) with long-lasting fluorescent properties and dimensional stability while being sustainable and functional. Thus, a well-known seed-mediated growth strategy has been developed to manufacture AgNCs supported onto carboxyl and aldehyde modified cellulose nanofiber (DATCNF) with ultra-small and intense fluorescence. The DATCNF acts as a reductant, template, and stabilizer while the protective ligand, 2-Mercaptonicotinic Acid (2-H₂MA), provides AgNCs with luminous characteristic and constrained size of 4.47 nm. The structural feature of 2-H₂MA also governs the formation and stability of AgNCs, imparting them with hydrophobic nature and steady fluorescence emission in water. This aqueous colloidal suspension (DATCNF-AgNCs) is highly dispersed, photobleaching resistant, and hardly agglomerates. Even after two months of exposure to the sun, the fluorescence intensity had only fallen by 20 %. Furthermore, the aqueous colloidal suspension exhibits outstanding antibacterial property and UV shielding capability, making it suitable as an additive for the production of TCNF films with high UV blocking capacity and high tensile strength. This strategy opens the door to design and fabricate mechanically robust DATCNF-AgNCs composites for luminescent, antimicrobial, and UV protection applications.

We investigate the effects of water-processable celluloses on the charge-transport properties in the conducting polymer composites and their solid-state organic electrochemical transistors (OECTs). Water-soluble methyl cellulose (MC) and water-dispersible cellulose nanofiber (CNF) are blended with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) in solution and used as a conductive channel. Both cellulose-PEDOT:PSS composites show fibrillar structures in thin films with respective dimensions of cellulose. The electrical conductivity was increased with 5-10 wt% of cellulose in the composite. The solid-state OECTs show better performance when the ionogel contains 1-ethyl-3-methylimidazolium triflate (EMIM:OTf) compared to the system with the commonly used EMIM bis(trifluoromethyl sulfonyl)imide (EMIM:TFSI). The MC-PEDOT:PSS composite paired with an EMIM:OTf-based ionogel exhibits a high figure-of-merit (μC^⁎) of OECTs of >50 F cm^-1 V^-1 s^-1 and an on-to-off current ratio of >10³. Our results show that cellulose and EMIM:OTf are compatible with PEDOT:PSS and that appropriate materials pairing can improve the properties of PEDOT:PSS-based composites and the performance of their electrochemical devices.

Cyclodextrins (CDs) are cyclic polysaccharides characterized by their unique hollow structure, making them highly effective carriers for pharmaceutical agents. CD-based delivery systems are extensively utilized to enhance drug stability, increase solubility, improve oral bioavailability, and facilitate controlled release and targeted delivery. This review initially provides a concise overview of nano drug delivery systems, followed by a detailed introduction of the structural features and benefits of CDs. It further summarizes the applications of CD-based delivery systems and offers insights for the rational design of drug delivery systems. In this review, CD-based delivery systems are categorized into several types, such as covalently modified CD derivatives, non-modified CD inclusion complexes, poly-cyclodextrins and others. The application of CD-based systems for the delivery of genetic therapeutic agents and co-delivery of gene and drug is also presented. Finally, this review discusses potential challenges and opportunities that may arise in the future. With the development of nanotechnology and optimization of preparation process, CD-based drug delivery systems will provide a more effective, precise and safe approach to drug therapy.